** B.E. (Fourth semester) EXAMINATION,DEC, 2004**

**(Common for EC/EE/EX Engg.)**

**(DIGITAL CIRCUIT AND SYSTEM)**

**(CS-402/4505)**

** **

Note: Attempt any five questions. All question carry equal marks.

1. (a) Draw K- map for the functions f_{?} = AB + BD +? B C and f_{? = }? B + B D

Hence , draw K-maps for functions f_{1 = }f? f? and f_{2 = }f? + f_{? .}

_{ } Simplify Y = (B + ?) (A+B+D) D and implement using only NAND gates.

2. (a) Draw the circuit of full adder using two half adder and gates.

(b) Design a full- subtractor circuit with3-input x,y,z ant two output D and B. The circuit subctracts x-y-z,

where z is the input borrow B is the outout borrow and D is the difference.

3. (a) How are the multavibrator classified? Explain the difference between various types of

multavibrator.

(b) Explain the working of one short with the help of suitable diagram.

4. (a) What is meant by open collector output of TTL gate? What is its utility? Draw the circuit showing

open collector output pull-up resister.

(b) What is meant by wired and collection of digital ICs what is its advantages? Draw a circuit og TTL

gates with wired and connection .

5. (a) Design a code converter which convert 3-bits binary no. to grey code.

(b) Using 4×1 MUX implement the following the Boolean function :

F (A,B.C) = ? (1,3,5,6)

6. (a) Design a mode -6 ripple counter with a provision to avoid lockout condition.

(b) What t is a switch tail counter? Give its application.

7. (a) What is meant by PLA ? Draw a block diagram and explain its working.

(b) Implement the following to Boolean functions with a PLA (Give only PLA programming table) :

F_{1} (A,B,C) = ? (0,1,2,4)

F_{2 } (A,B,C) = ? (0,5,6,7)

8. Write short notes on any two of the following:

(i) D/A converter

(ii) Sample and hold circuit

(iii) Look-ahead carry generator

(iv) Schmitt trigger